"Liberty's Kids" is great set of cartoons about the American Revolution. I think it is streamable for free somewhere but the 4 DVD set is currently 7.99 on Amazon, up from the 4.99 when I bought it. The primary difference between the cheap version and the $50-$75 versions is that the more expensive ones have a public display license so they can be used in schools legally while the <$10 versions are only licensed for home use.
From reading the Amazon reviews lots of the watchers are AP US History students. My kids both enjoyed watching them around age 5.
